readlink --version (return code: 0)
readlink (GNU coreutils) 8.25
Copyright (C) 2016 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Written by Dmitry V. Levin.
readlink --help (return code: 0)
Usage: readlink [OPTION]... FILE...
Print value of a symbolic link or canonical file name
-f, --canonicalize canonicalize by following every symlink in
every component of the given name recursively;
all but the last component must exist
-e, --canonicalize-existing canonicalize by following every symlink in
every component of the given name recursively,
all components must exist
-m, --canonicalize-missing canonicalize by following every symlink in
every component of the given name recursively,
without requirements on components existence
-n, --no-newline do not output the trailing delimiter
-q, --quiet,
-s, --silent suppress most error messages
-v, --verbose report error messages
-z, --zero end each output line with NUL, not newline
--help display this help and exit
--version output version information and exit
GNU coreutils online help: <http://www.gnu.org/software/coreutils/>
Full documentation at: <http://www.gnu.org/software/coreutils/readlink>
or available locally via: info '(coreutils) readlink invocation'